Fix String.prototype.repeat() copy_size handling
Fix String.prototype.repeat() copy_size handling

copy_size was computed incorrectly when DUK_USE_PREFER_SIZE is false.
The bug caused memory unsafe behavior.

harold-b/duktape,svaarala/duktape,svaarala/duktape,markand/duktape,harold-b/duktape,harold-b/duktape,svaarala/duktape,markand/duktape,markand/duktape,svaarala/duktape,svaarala/duktape,harold-b/duktape,harold-b/duktape,svaarala/duktape,harold-b/duktape,svaarala/duktape,markand/duktape,harold-b/duktape,svaarala/duktape,markand/duktape,markand/duktape,svaarala/duktape,markand/duktape,harold-b/duktape,markand/duktape,markand/duktape,harold-b/duktape,markand/duktape,harold-b/duktape